Checking Air Conditioning (A/C) Relay Signal And Air Conditioning (A/C) Compressor Signal
Checking air conditioning (A/C) relay signal and air conditioning (A/C) compressor signal
Checking air conditioning (A/C) relay signal
- Start the engine and idle it.
- Air conditioning (A/C) switch on.
- Blower fan on:
- Select Volvo Scan Tool (ST) to read off the status of the air conditioning (A/C) relay.
Is the A/C relay on?
Yes - Checking the air conditioning (A/C) compressor signal
No - Connecting breakout box B
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Checking the air conditioning (A/C) compressor signal
- Start the engine and idle it.
- Air conditioning (A/C) switch on.
- Blower fan on.
Select Volvo Scan Tool (ST) to read off the status of the air conditioning (A/C) compressor while the compressor is running.
Is the compressor on?
Yes - Cleaning idle air control (IAC) valve connector
No - Connecting breakout box B
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Cleaning idle air control (IAC) valve connector
- Clean and grease engine control module (ECM) and idle air control (IAC) valve connectors. Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.
Check whether the engine speed still dips
Do the fault symptoms persist?
Yes - Replacing component
No - FAULT FOUND
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Replacing component
- Try a new idle air control (IAC) valve.
Continue - FAULT FOUND
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Checking air conditioning (A/C) compressor signal cable
- Ignition off.
- Breakout box connected.
- Connect control module.
- Air conditioning (A/C) switch on.
- Blower fan on.
- Start engine.
- Connect a voltmeter between connectors #6 (#B6) and #28 (#B28) on the breakout box.
The voltmeter should read battery voltage when the compressor is running.
OK - Checking for contact resistance and oxidation
Not OK - Checking for an open-circuit
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Checking for contact resistance and oxidation
- The cause of dipping has been contact resistance in the engine control module (ECM) connector. Clean and grease engine control module (ECM) connector according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.
Continue - FAULT FOUND
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Checking for an open-circuit
- Check cable between #B6 and pressure switch (Pressostat) connector (7/53) terminal 2 for an open-circuit according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.
Continue - FAULT FOUND
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Checking air conditioning (A/C) relay signal cable
- Ignition off.
- Breakout box connected.
- Connect control module.
- Air conditioning (A/C) switch on.
- Blower fan on.
- Start engine.
Connect a voltmeter between connectors #25 (#B25) and #28 (#B28) on the breakout box.
The voltmeter should read battery voltage when the compressor is running.
OK - Checking for contact resistance and oxidation
Not OK - Checking for an open-circuit
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Checking for contact resistance and oxidation
- The cause of dipping has been contact resistance in the engine control module (ECM) connector. Clean and grease engine control module (ECM) connector according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.
Continue - FAULT FOUND
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Checking for an open-circuit
- Check cable between #B25 and pressure switch (Pressostat) connector (7/53) terminal 1 for an open-circuit according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.
Continue - FAULT FOUND
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Connecting breakout box B
Connecting breakout box (connector B)
Connecting the breakout box
Is the breakout box connected to the Motronic 4.4 connector?
Yes - No Fault Found
No - Connecting breakout box to Motronic 4.4 connector B (gray)
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Connecting breakout box to Motronic 4.4 connector B (gray)
- Ignition off.
- Disconnect control module.
Note! The engine control module (ECM) must not be removed from the car until the main relay has interrupted its power supply. This may take up to 150 seconds (cars with an immobilizer 245 seconds) after the ignition has been switched off.
Connect adapter 951 1351 ADAPTOR 86-PIN 951 1351 Adaptor 86-Pin to engine control module (ECM) connector and connect breakout box 981 3190 Replaced by 9511428 981 3190 Replaced by 951 1428 to adapter.
Continue - Checking ground terminal #B28
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Checking ground terminal #B28
- Ignition off.
- Switch off all equipment that takes power from the battery (courtesy lighting, radio etc).
- Connect control module.
- Connect an ohmmeter between #28 (#B28) on the breakout box and battery negative terminal.
The ohmmeter should read approximately 0 ohms.
OK - Reading is OK
Not OK - Checking for an open-circuit
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Checking for an open-circuit
- check ground terminals 31/32 and 31/33 on the engine and their cables for an open-circuit according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault and contact resistance and oxidation according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.
Continue - No Fault Found
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Reading is OK
- Return to the fault-tracing procedure where it was interrupted.
Continue - No Fault Found
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FAULT FOUND - Checking air conditioning (A/C) compressor signal cable
No Fault Found - Checking air conditioning (A/C) compressor signal cable
FAULT-TRACING FAILED - Checking air conditioning (A/C) compressor signal cable
CONNECTED - Checking air conditioning (A/C) compressor signal cable
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Connecting breakout box B
Connecting breakout box (connector B)
FAULT FOUND - Checking air conditioning (A/C) relay signal cable
No Fault Found - Checking air conditioning (A/C) relay signal cable
FAULT-TRACING FAILED - Checking air conditioning (A/C) relay signal cable
CONNECTED - Checking air conditioning (A/C) relay signal cable
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